Polymerizing chloroprene in the presence of xanthogen disulphides with functional groups

ABSTRACT

WHEREIN X H, alkyl, aryl, aralkyl or halogen N 1 TO 20, A PROCESS FOR PREPARING THEM, A PROCESS FOR POLYMERISING DIENES AND MONOETHYLENICALLY UNSATURATED COPOLYMERIZABLE MONOMERS IN THE PRESENCE OF THESE PARTICULAR XANTHOGEN DISULPHIDES AND TO VULCANISABLE RUBBER MIXTURES CONSISTING OF AN UNCROSS-LINKED BENZENE SOLUBLE CHLOROPRENE HOMOPOLYMER OR COPOLYMER WHICH IS PREPARED IN THE PRESENCE OF SAID XANTHOGEN DISULPHIDES.   or   in which R is the same or different and denotes the following groups:   This invention relates to xanthogen disulphides of the formula

A United States Patent [191 Mayer-Mader et al.

1 Dec. 16, 1975 POLYMERIZING CHLOROPRENE IN THE PRESENCE OF XANTHOGEN DlSULPl-llDES WITl-l FUNCTIONAL GROUPS [75] Inventors: Rudolf MayerMader; Wilhelm G'dbel, both of Cologne, Germany [73] Assignee: Bayer Aktiengesellschaft, Germany [22] Filed: Feb. 6, 1974 [21] Appl. N0.: 440,014

[30] Foreign Application Priority Data Feb, 10, 1973 Germany 2306610 May 23, 1973 Germany 2352937 [52] US. 260/92.3; 260/795 C; 260/807;

Primary ExaminerJoseph L. Schofer Assistant Examinerl-lerbert .l. Lilling Attorney, Agent, or Firm-Connolly and Hutz 57 ABSTRACT This invention relates to xanthogen disulphides of the formula in which R is the same or different and denotes the following groups:

X H, alkyl, aryl. aralkyl or halogen n 1 to 20,

wherein X H, alkyl, aryl, aralkyl or halogen n 1 to 20,

a process for preparing them, a process for polyme rising dienes and monoethylenically unsaturated copolymerizable monomers in the presence of these particular xanthogen disulphides and to vulcanisable rubber mixtures consisting of an uncross-linked benzene soluble chloroprene homopolymer or copolymer which is prepared in the presence of said xanthogen disulphides.

6 Claims, No Drawings 1 POLYMERIZING CHLOROPRENE [N THE PRESENCE OF XANTHOGEN DlSULPI-IIDES WITH FUNCTIONAL GROUPS in which R is the same or different and denotes the following groups:

wherein X H. alkyl aryl, aralkyl or halogen n l to 20;

alkyl groups containing l to 6 carbon atoms (methyl. ethyl, isopropyl, hexyl). phenyl. naphthyl, benzyl, chlorine, bromine and iodine being preferred.

The invention particularly relates to those xanthogen disulphides of the general formula I in which the two groups R are identical and the group X denotes hydrogen or alkyl (preferably C, C

Another object of this invention is a process for producing xanthogen disulphides of formula I wherein as alcohol of the formula ROH in which R has the meaning indicated above is reacted with carbon disulphide in the presence of a strong alkali to form the alkali metal xanthate which is then oxidised to the xanthogen disulphide. Alcohols with the following groups R are particularly suitable for this process:

The process is generally carried out as follows: Starting from an aqueous solution of an alkali, e.g. a 20 5O auqeous potassium or sodium hydroxide solution, approximately equimolar quantities of an alcohol ROH (in which R has the meaning defined above) are added. Carbon disulphide is slowly added to this mixture. The carbon disulphide may be added in equimolar quantities or in an excess. An exothermic reaction immediately sets in to form the xanthate. During this reaction,

the mixture is cooled so that the reaction temperature does not rise above 50C.

The reaction may be represented as follows:

in which M alkali metal and R has the meaning defined above.

The aqueous xanthate solution obtained is then oxidised to xanthogen disulphide by the addition of a suitable oxidising agent such as hydrogen peroxide or potassium peroxydisulphate (as aqueous solution). The water-insoluble xanthogen disulphide precipitates. It is separated from the aqueous phase. e.g. by filtration or decanting, and dried. The reaction may be represented as follows:

R has the meaning defined above.

This process is carried out similar to the process for producing dialkyl xanthogen disulphides as described, for example, in Kirk-Othmer, Encyclopedia of Chemical Technology, 2nd Edition, Vol. 22 (I970), pages 4l9 429 and in Ullmann Encyclopedia der Techn. Chemie" Vol. 18 (1967) pages 7l8 728.

Another object of this invention is a process for polymerising one or more conjugated diolefines and copolymerising one or more conjugated diolefines with monoethylenically unsaturated copolyrnerizable monomers in the presence of radical forming initiators, in the presence of xanthogen disulphides of the general formula l as molecular weight modifiers. Particularly suitable conjugated diolefines are those which contain 4 to 8 carbon atoms such as butadiene, isoprene, piperylene, chloroprene and 2,3-dichlorobutadiene.

In more detail this invention relates to aprocess for producing chloroprene polymers which are easy to process, wherein a. 60 to 100 parts by weight of chloroprene and 40 to parts by weight of a diene in which the hydrogen atoms may be partly or completely substituted by halogen atoms and/or of an monoethylenically unsaturated copolymerizable monomer are polymerised in the presence of 0.05 to 30 parts by weight, preferably 0.15 to pans by weight and especially 0. [5 to 1 parts by weight of a xanthogen disulphide of the formula 1 in aqueous dispersion.

The monoethylenically unsaturated copolymerizable monomers used are preferably acrylonitrile, styrene and ethylacrylate. These comonomers are usually present in quantities of up to 40 7c by weight, based on the diolefine. Suitable radical forming polymerisation catalysts are, for example, peroxides and azo compounds or so-called redox systems. The following are examples: Cumene hydroperoxide, pinene hydroperoxide, potassium peroxidisulphate, tert.-butyl peroxide, azo-bisisobutyronitrile. Redox systems are: peroxides. e.g. cumene hydroperoxide, in combination with reducing compounds, e.g. formaldehyde sulphoxylate, iron salts of fonnamidine sulphinic acid.

The polymerisation is preferably carried out in aqueous emulsion. An aqueous emulsifier solution starting from an "aqueous phase" which contains at least 0.] to 5 7( by weight of an emulsifier is provided. Suitable emulsifiers are e.g. alkali metal alkyl sulphonates, alkali metal sulphates. long chain carboxylic acids. resinic acids and polyether alcohols. The monomer or monomers together with 0.05 to 30 7( by weight, preferably ().l5 to l 72 by weight. based on the monomers of a dialkylxanthogen disulphide of formula l are then emulsified in this aqueous phase and the radical forming initiator is added. Polymerisation is preferably carried out at temperatures of from 50 to 100C, preferably 5 to 50C. This process is basically known for polymerising chloroprene, e.g. from US. Pat. Nos. 3,042,652; 3,147,317 and 3.147318.

When 50 to 100 7r. preferably 50 to 7( of the monomers have been polymerised. unreacted mono mer is removed and then the polymer is recovered from the aqueous emulsion by electrolyte precipitation or freezing coagulation and drying. In this polymerisation or freezing coagulation and drying. In this polymerisation the xanthogen disulphide of formula I act as molecular weight modifiers, i.e. they reduce the molecular weight of the resulting polymers compared with the molecular weight of polymers obtained in the absence of xanthogen disulphide. This becomes apparent by comparing the Mooney viscosities of the resulting products.

The xanthogen disulphides of formula I are particularly suitable for modifying the molecular weight of chloroprene polymers. Chloroprene polymers obtained in their presence yield vulcanisates of improved mechanical properties.

This is particularly pronounced in mixtures of un cross-linked benzene soluble polychloroprenes made in accordance with this invention and benzene insoluble. slightly cross-linked polychloroprenes. These mixtures are easy to process and their vulcanisates have particularly high tensile strength.

The tensile strength of these vulcanisated polymers can be even further improved by vulcanising in the presence of agents, such as masked diisocyanates, which react with the end groups of the xanthogen disulphides.

Another object of this invention is therefore a mixture of an uncross-linked, benzene soluble chloroprene polymer (a) made from chloroprene and optionally up to 40 by weight (based on the monomer mixture) of an ethylenically unsaturated copolymerizable monomer in the presence of0.05 30 7c by weight (based on the monomers) of a xanthogen disulphide of formula 1 and a cross-linked, benzene insoluble chloroprene polymer (b).

The benzene soluble chloroprene polymer (a) in this mixture is the product described above.

In more detail this invention relates to a process for producing chloroprene polymer mixtures which are easy to process wherein a. 60 to parts by weight of chloroprene and 40 to 0 parts by weight of a diene in which the hydrogen atoms may be partly or completely substituted by halogen atoms and/or of an ethylenically unsaturated copolymerizable monomer are polymerised in the presence of 0.05 to 30 parts by weight, preferably 015 to 5 parts by weight and especially 0.15 to 1 part by weight of a xanthogen disulphide of the formula I in aqueous dispersion to produce an uncross-linked. benzene soluble polymer which is then mixed with b. a cross-linked. benzene insoluble chloroprene homopolymer or copolymer consisting of 80 to I parts by weight of chloroprene and 20 to 0 parts by weight of a divinyl compound and/or an monoethylenically unsaturated copolymerizable monomer. the components A and B being mixed in a ratio by weight of between 20 l and l 20. preferably between I l and 7 l.

The invention relates also to mixtures of to 95 parts by weight. preferably 55 to 90 parts by weight of an uncross-linked. benzene soluble chloroprene homopolymer or copolymer consisting of 60 to I00 parts by weight of chloroprene and 40 to 0 parts by weight of a diene in which the hydrogen atoms may be partly or completely replaced by halogen atoms and/or of an monoethylenically unsaturated copolymerizable monomer which has been preparred in the presence of 0.05 to 30 parts by weight. preferably 0.15 to 5 parts by weight and especially 0.15 to 1 part by weight of an xanthogen disulphide of formula I and 95 to 5 parts by weight, preferably 45 to parts by weight. ofa crosslinked, benzene insoluble chloroprene homopolymer or copolymer of 80 to I00 parts by weight of chloroprene and to 0 parts by weight of a divinyl compound and/or an a-olefine.

Suitable benzene insoluble cross-linked chloroprene polymers can be prepared by various methods which yield cross-linked polymer in the latex form, for example the chloroprene may be polymerised to a high degree of conversion in the absence of a chain transfer agent or with only small quantities of such agent, e.g. an alkylmercaptan or dialkylxanthogen disulphide. A suitable method of carrying out such a process to a high degree of polymerisation has been described, for exam ple in U.S. Pat. No. 3,147,317. In another method of making cross-linked chloroprene polymer a comonomer which is capable of copolymerising with the chloroprene and which contains two or more polymerisable double bonds is added in the polymerisation. Comono mers suitable for this purpose are, for example, divinylbenzene and esters of methacrylic acid and polyhydroxy compounds such as alkylene glycols, dihydroxybenzene or trimethylpropane.

Cross-linked chloroprene polymers are obtaianed by the same methods as known for making benzene soluble chloroprene polymers but monomer conversion is raised to. eg 90 to 100 In another method of preparing suitable cross-linked chloroprene polymers the latex of an uncross-linked chloroprene polymer is subjected to a post-treatment which effects cross-linking. Such post-treatment is e.g. irradiation according to U.S. Pat. No. 3,042,652 and treatment with an organic peroxy compound accoding to U.S. Pat. No. 3.l47.3l8.

In the cross-linked polymer part of the chloroprene, up to about 20 can be re placed by another monomer. Suitable comonomers are the same as with the benzene soluble polymers described above.

The benzene insoluble chloroprene polymer is pref erably a copolymer of chloroprene and 2 to 20 7r by weight (based on chloroprene) of a diester of a dillydric aliphatic alcohol and an acrylic acid. These dies ters have the general formula I ll ll 0 in which R and R represents hydrogen. alkyl containing 1 to 4 carbon atoms or chlorine and X represents an alkylene group containing 2 20 carbon atoms.

The following are examples of such compounds: ethylene dimethacrylate, propylene dimethacrylate, butylene dimethacrylate. isobutylene dimethyacrylate. ethylene diacrylate, propylene diacrylate. butylenc diacrylate and isobutylene diacrylate.

These products are made in accordance with the usual methods of polymerising chloroprene and of copolymerising butadiene and acrylonitrile in aqueous emulsion. The procedure and the products obtained from it are disclosed in British Patent No. l.l58.970.

The components of the elastomer mixture are preferably combined by vigorously mixing the latices and then recovering the solid polymer mixture by the usual methods, e.g. freezing coagulation (U.S. Pat. No. 2.187.146) or drying on rollers (U.S. Pat. No. 2.9l4 497). Elektrolyte precipitation is also possible. Alternatively. the components can be recovered individually by the usual methods and then be mixed mechanically. eg by kneading on mixing rollers or in an internal mixer such as a Banbury mixer or a Werner- Pfleiderer mixer.

In the case of polychloroprene, the weight ratio of benzene soluble component (a) to cross-linked component (b) may be from 20 I to l 20. preferably from I l to 7 l. The mixture should contain at least 50 9? by weight of benzene soluble component (a).

The polychloroprene mixtures according to the invention can be compounded to form vulcanisable rubber mixtures and vulcanised in the same way as conventional polychloroprenes. They are used for all purposes for which polychloroprenes are suitable.

Their primary advantage is improved processing compared to benzene soluble polychloroprene and to benzene insoluble polychloroprenes taken alone. Compared to known mixtures of benzene soluble and benzene insoluble polychloroprenes. their thermal stability is substantially improved.

When benzene soluble polychloroprenes made in the presence of xanthogen disulphides of formula I are compared to those made in the presence of mercaptans as molecular weight modifiers. they are found to be superior in the tensile strengths of the vulcanisates. The tensile strengths can be even further improved by vulcanising with masked diisocyanates.

Examples of the preparation of xanthogen disulphides which contain alkoxy groups A. EXAMPLE I Xanthogen disulphide of hexane triol monoacetal To prepare the xanthogen disulphide of hexane triol monoacetal, 88 g of sodium hydroxide and 90 g of distilled water are introduced into a 3 liter flask and the sodium hydroxide is dissolved with stirring. 292 g of hydroxy-hexanel ,2-diol acetal (hexantriolmonoacetal) of the following formula a are then added and the reaction mixture is stirred for 2 hours. It is then cooled to 10C and 184 g of carbon disulphide are added dropwise with stirring. The tern perature should not rise above 20C during this operation. When all the carbon disulphide has been added, the whole mixture is stirred for a further 2 hours.

A solution consisting of 300 g of ammonium persulphate and 2 litres of distilled water is then added dropwise to the reaction mixture in which the xanthate has been formed. The xanthogen disulphide which is formed by oxidation is then removed from the aqueous phase washed with distilled water and taken up in ether. and the ethereal phase is dried with anhydrous 20 sodium sulphate. The solvent is removed in a rotary evaporator. The yield of xanthogen disulphide is 361) g.

Xanthogen disulphide of hexane triol monoketal To prepare the xanthogen disulphide of hexane triol monoketal. 88 g of sodium hydroxide and 90 g of dis- 3s tilled water are introduced into a 3 liter flask and the sodium hydroxide is dissolved with stirring. 348 g of fi-hydroxy-hexane-l .2-diolmonoketal (hexane triol monoketal of formula b are then added and the mixture then stirred for a further 2 hours. The reaction mixture is then cooled to C and 184 g of carbon disulphide are added dropwise with stirring, during which time the temperature should not rise above C. Stirring is continued for another 2 hours after all the carbon disulphide has been added.

A solution consisting of 300 g of ammonium persul phate and 2 litre of distilled water is then added dropwise into the reaction mixture containing the xanthate which has been formed in the reaction. The xanthogen disulphide obtained by oxidation is then separated from the aqueous phase, washed with distilled water and taken up in ether and the ethereal phase is dried with anhydrous sodium sulphate. The solvent is evaporated o en.

in a rotary evaporator. The yield of xanthogen disulphide is 358 g.

( ll l EXAMPLE 3 Xanthogen disulphide of glycerol monoacetals To prepare xanthogen disulphides of glycerol monoacetals. 88 g of sodium hydroxide and 90 g of distilled water are introduced into a 3 l flask and the sodium hydroxide is dissolved with stirring. 264 g of a mixture of glycerol monoacetals of formulae C and C which are obtained by reacting glycerol with formaldehyde are then added and stirring is continued for 2 hours.

The reaction mixture is then cooled to 10C. 184 g of carbon disulphide are then added dropwise with stirring; the temperature should not rise above 20C during this operation. Stirring is continued for 2 hours after all the carbon disulphide has been added.

A solution consisting of 300 g of ammonium persulphate and 2 liters of distilled water is then added dropwise to the reaction mixture of the resulting xanthatesr The xanthogen disulphides formed by oxidation are then separated from the aqueous phase, washed with distilled water and taken up with ether and the ethereal phase is dried with anhydrous sodium sulphate. The solvent is removed in a rotary evaporator. The yield of xanthogen disulphides is 250 g.

Xanthogen disulphide of glycerol monoketal To prepare the xanthogen disulphide of glycerol monoketal. 88 g of sodium hydroxide and 90 g of dis and stirring is continued for 2 hours. The reaction mixture is then cooled to 10C. 176 g of carbon disulphide are then added with stirring; the temperature should not rise above 20C during this operation. After all the carbon disulphide has been added, the reaction mixture is stirred for another 2 hours. A solution consisting of 300 g of ammonium persulphate and 2 liters of distilled water is then added dropwise to the reaction mixture containing the resulting xanthate. The xanthogen disulphide obtained by oxidation is then separated from the aqueous phase. washed with distilled water and taken up in ether and the ethereal phase is dried with anhydrous sodium sulphate. The solvent is removed in a rotary evaporatorv The yield of xanthogen disulphide is 270 g.

II S

EXAMPLE 5 Xanthogen disulphide of l,l.l-tris-hydroxymethylpropane monoacetal To prepare the xanthogen disulphide of l,l.l-trishydroxymethyl-propane monoacetal, 88 g of sodium hydroxide and 90 g of distilled water are introduced into a 3 liter flask and the sodium hydroxide is dissolved with stirring. 292 g of the monoacetal of formula e are then added and stirring is continued for 2 hours. The reaction mixture is then cooled to l0C and 176 g of carbon disulphide are added with stirring. The temperature should not rise above 20C during the addition of carbon disulphide. The reaction mixture is stirred for another 2 hours after all the carbon disulphide has been added. A solution consisting of 300 g of ammonium persulphate and 2 liters of distilled water is then added dropwise to the reaction mixture containing the resulting xanthate. The xanthogen disulphide obtained on oxidation is then separated from the aqueous phase, washed with distilled water and taken up in ether and the ethereal phase is dried with anhydrous sodium sulphate. The solvent is removed in a rotary evaporator.

The yield of xanthogen disulphide is approximately 350 g.

o C-CH -OC-S 2 l0 l C H S B. l. EXAMPLE OF POLYMERISATION The following phases are prepared separately and introduced into the polymerisation vessel:

onomcr phase 100 parts by weight of chloroprenc y parts by weight of xunthogcn disulphide of hexane triol monoacetal Aqueous phase 120 parts by weight of distilled water 5 parts by weight of sodium salt of a disproportionated abietic acid sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde sodium hydroxide tetrasodium pyrophosphate (L5 parts by weight of parts by weight of parts by weight of The quantity y of modifier is varied as follows:

(I 5 parts by weight 0.75 parts by weight (Hill parts by weight parts by weight quantities of modifier as follows:

y Regulator Mooney-viscosity Z by weight ML-4llU()C y, 0.5 y- (1.75 57 y" 0.80 50 1.00 32 a. EXAMPLE OF POLYMERISATION The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase llll) Parts by weight of 7 Parts by eight of chloroprene santhogen disulphide of l. l l -trish \dro\ymeth lpropane monoacetal A ueous phase \ZO Parts by weight of distilled water Parts by weight of sodium salt of a disproportionated abietie acid ()5 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 0.5 parts by weight of sodium hydroxide ().5 parts by weight of tctrasodium pyrophosphate The quantity 1 of modifier was varied as follows:

7, (H Part by weight z. ()5 Part by weight 2;, l,() Part by weight 1 Regulator Mooney viscosity 5 by weight Ml.-4'/l(ltlC 1]]. EXAMPLE OF POLYMERlSATlON (COMPARISON EXAMPLE) The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase 100 Parts by weight of (L45 Parts by weight of Aqueous phase chloroprene diisopropyl xanthogen disulphide I Parts by weight of distilled water 5 Parts by weight of sodium salt of a disproportionated abietic acid (15 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde (15 Parts by weight of sodium hydroxide (15 Parts by weight of tetrasodium pyrophosphate When the two phases have been mixed, the temperature is raised to 43C and polymerisation is released by an activator solution consisting of 2.5 parts by weight of formamidine sulphinic acid and 97.5 parts by weight of distilled water. The activator solution is added dropwise as required.

When 65 to 70% of the monomer has been converted to polymer, the remaining monomer is removed by 12 steam distillation and the polymer is isolated from the latex by electrolyte precipitation and dried. The polymer has a Mooney viscosity of approximately 44.

IV. EXAMPLE OF POLYMERlSATlON (COMPARISON EXAMPLE) The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase IUU Parts by weight of 028 Parts by weight of chloroprcne n DDM (normal dodec) lmercaptanl Agueous phase 120 Parts by weight of distilled water 5 Parts by weight of sodium salt of a disproportionated abietic acid ()5 Parts by eight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde sodium hydroxide tetrasodiumpy rophosphate Parts by weight of Parts by weight of When the two phases have been mixed, the temperature is raised to 43C and polymerisation is initiated with an activator solution consisting of 2.5 parts by weight of formamidine sulphinic acid and 97.5 parts by weight of distilled water. The activator solution is added dropwise as required. When 65 to of the monomer has been converted to polymer, the remaining monomer is removed by steam distillation and the polymer is isolated from the latex by electrolyte p recipitation and dried. The polymer has a Mooney viscosity of approximately 43.

V. EXAMPLE OF POLYMERISATION (COMPARISON EXAMPLE) The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase IUU Parts by weight of chloroprene 04 Parts by weight of diethyl xanthogen disulphide Agueous phase I20 Parts by weight of distilled water 5 Parts by weight of sodium salt of a disproportionated abietic acid 0.5 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 0.5 Parts by weight of sodium hydroxide ()5 Parts by weight of letrasodium pyrophosphatc When the two phases have been mixed, the temperature is raised to 43C and polymerisation is initiated with an activator solution consisting of 2.5 parts by weight of formamidine sulphinic acid and 97.5 parts by weight of distilled water. The activator solution is added dropwise as required. When 65 to 70% of the monomer has been converted to polymer, the remaining monomer is removed by steam distillation and the polymer is isolated from the latex by electrolyte precipitation and dried. The polymer has a Mooney viscosity of approximately 43.

VI. EXAMPLE OF POLYMERISATION (COMPARISON EXAMPLE) The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase I00 Parts by weight of 055 Parts by weight of chloroprene xanthogen disulphide of ethylene glycol monomethylether -continued Agucous phase l 30 Parts by eight of distilled water 5 Parts by vtcight of sodium salt of a disproportionated abietic acid 0.5 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 05 Parts by weight of sodium hydroxide 0.5 Parts by weight of tetrasodium pyrophosphate When the two phases have been mixed. the temperature is raised to 43C and polymerisation is initiated with an activator solution which consists of 2.5 parts by weight of formamidine sulphinic acid and 97.5 parts by weight of distilled water. The activator solution is added dropwise as required. When 65 to 75% of the monomer has been converted to polymer, the remaining monomer is removed by steam distillation and the polymer is isolated from the latex by electrolyte precipitation and dried. The polymer has a Mooney viscosity of approximately 43.

VII. EXAMPLE OF POLYMERISATION (COMPARISON EXAMPLE) The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase I Parts by weight of chloroprenc 0.55 Parts by weight of xanthogen disulphide of ethylene glycol monocthyl ether 035 Parts by weight of sulphur Aqueous phase I20 Parts by weight of distilled water Parts by weight of sodium salt of a disproportionatcd abietic acid 0.7 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 0.8 Parts by weight of sodium hydroxide 05 Parts by weight of tetrasodium pyrophosphute When the two phases have been mixed, the temperature is raised to 43C and polymerisation is initiated with an activator solution which has the following composition: 1.3 Parts of distilled water, 0.04 parts of potassium persulphate and 0.04 parts of anthraquinone sulphonic acid sodium salt. The activator solution is added as required. When between 65 and 95% of the monomer (depending on the desired viscosity) has been converted to polymer, the remaining monomer is removed by steam distillation and the polymer is isolated by electrolyte precipitation and dried.

Vlll. EXAMPLE OF POLYMERISATION (COMPARISON EXAMPLE) The following phases were prepared separately and introduced into the polymerisation vessel:

Monomer phase I00 Parts by weight of chloroprene 0.4 Parts by weight of xanthogen disulphide of ethanol 035 Parts by weight of sulphur Aqueous phase 120 Parts by weight of distilled water 5 Parts by weight of sodium salt of a disproportionated abietic acid 0.7 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 08 Parts by weight of sodium hydroxide ()5 Parts by weight of tetrasodium pyrophosphatc When the two phases have been mixed, the temperature is raised to 43C and polymerisation is initiated with an activator solution of the following composition: 1.3 Parts of distilled water. 004 parts of potassium persulphate and 0.04 parts of anthraquinone sulphonic acid sodium salt. The activator solution is added as required. When between 65 and of the monomer (depending on the desired viscosity) has been converted to polymer, the remaining monomer is removed by steam distillation and the polymer isolated by electrolyte precipitation and dried.

IX. EXAMPLE OF POLYMERISATION The following phases are prepared separately and introduced into the polymerisation vessel:

Monomer phase l00 Parts by weight of chloroprene 0.85 Parts by weight of xanthogcn disulphide of heyanetriol nionoacetal 0.35 Parts by weight of sulphur Aqueous ph s e 120 Parts by weight of distilled water 5 Parts by weight of sodium salt of a disproportionated abietic acid 07 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 0.8 Parts by weight of sodium hydroxide 0.5 Parts by weight of tetrasodium pyrophosphate When the two phases have been mixed. the temperature is raised to 43C and polymerisation is initiated with an activator solution of the following composition: l.3 Parts of distilled water. 0.04 parts of potassium persulphate and 0.04 parts of anthraquinone sulphonic acid sodium salt. The activator solution is added as required. When between 65 and 95% of the monomer (depending on the desired viscosity) has been converted to polymer. the remaining monomer is removed by steam distillation and the polymer is isolated by electrolyte precipitation and dried.

The polymers prepared under I IX are then mixed with the following components on rollers in the usual manner:

Formulation (a) Parts by weight of polychloroprenc 29 Parts by weight of inactive carbon black 05 Parts by weight of stearic acid 20 Parts by weight of phenyl-B naphthylamine 4.0 Parts by weight of magnesium oxide 50 Parts by weight of zinc oxide 0.5 Parts by weight of ethylene thiourca Formulation ((1) I00 Parts by weight of poly'chloroprene 29 Parts by weight of inactive carbon black 0.5 Parts by weight of stearic acid 2.0 Parts by weight of phenyl-Bmaphthylamine l.() Parts by weight of magnesium oxide 5.0 Parts by weight of zinc oxide 3.0 Parts by weight of TA-ll [RI IR] Vulcan lZLIllOI'I accelerator of Du Pont i NHCOHCH -CH N CH NHCOCH CH N(CH vulcanization is carried out at 15 1C for minutes. The vulcanizates obtained have the properties shown below (Table 1). It can be seen from Table 1 that the Table [I Benzene insoluble polychloroprene Benzene soluble polychloroprene hlghest Strength value? are Obtained when reguk}tors In 5 X1 85 Parts by weight 15 parts by weight the form of the particular xanthogen dlsulphldes of formula K'are (Example Formuliauon A Polymer Example I Polymer Example X difference is particularly marked when uslng a vuleanl H Polymer Example lV Polymer Example x zation accelerator which responds to the modified xan- C Pmlmc' Emmple Hump? X D Pol mer E\ample \l Polymer Example X thogen disulphldes of Formula 1 (Example I) Formula o tion B.

Table l Example Example Example Example Example I I" IV V Vl Formulation (a) Tensile strength (kg/em 159 I43 145 I44 I42 Elongation at break (it 630 640 615 681) 650 Modulus (300% elongation) kg/em 48/123 43/ I07 42/112 45/105 8/1 ll 1500' elongation) Hardness RT 57 55 53 58 5 7 Elasticity 56 54 52 5h 54 Formulation (/3 Tensile strength (kg/em") 177 l 15 Elongation at break ("4 8'70 925 Modulus (300 i elongation) kgrem 37/92 18/44 (500'? elongzltionl Hardness RT 57 48 Elasticity 58 53 X. EXAMPLE OF POLYMERISATION A. Preparation of the benzene insoluble polychloroprene as one of the components for preparing a mixture which has good properties for working up.

The following components are introduced into a 40 liter autoclave which 5 equipped with stirrer. thermom eter and feed tubes and connected to a cooling system: 35 14.4 I of salt-free water, 815 g of the sodium salt of a disproportionated abietic acid mixture, 72 g of a condensation product of an alkyl naphthalene sulphonic acid and formaldehyde, 36 g of sodium hydroxide, and 60 g of tetrasodium pyrophosphate. A solution containing the following constituents is then added: 10.620 g of chloroprene. 1.380 g of ethylene glycol dimethacrylate, 34 g of ndodecylmercaptan. The reaction mixture is then heated to 43C and polymerisation is initiated by dropwise addition of a catalyst solution containing 45 the following components:

25 g of f0 rmamidine sulphinic acid, dissolved in 97.5 g of distilled water. When approximately 80% of the monomer has been polymerised, polymerisation is stopped by the addition of a stabilizer solution of the following composition:

5 g of phenothiazine. and 5 g of p-tert.-butylpyrocatechol in 500 g of toluene. The latex is then freed from unreacted monomer.

B. Preparation of benzene soluble polychloroprene as one of the components for the preparation of a mix ture which has good properties for working up.

Preparation of the benzene soluble polychloroprene is carried out in accordance with polymerisation examples 1. 1V, V and VI.

85 Parts by weight of benzene soluble polymer component are mixed with 15 parts by weight of benzene insoluble polymer component (X) in the latex and the polymer is then isolated from the latex (Table 11).

Polymers X1 A to XI D are then mixed in accordance with Formulation a and Formulation B and vulcanized at 151C for 30 minutes.

I. PREPARATION OF UNCROSS-LINKED, BENZENE SOLUBLE CHLOROPRENE POLYMERS EXAMPLE 6 Monomer phase 100.00 Parts by weight of chloroprene 0.85 Parts by weight of xanthogen disulphide of the following formula A9 ucous ph use 120.0 Parts by weight of salt-free water 5.0 Parts by weight of sodium salt of a disproportionatcd abietic acid 0.5 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde Parts by weight of sodium hydroxide Parts by weight of tetrasodium pyrosphosphute When the two phases have been mixed, the temperature is adjusted to 43C and polymerisation is initiated with an activator solution consisting of 2.5 parts by weight of formamidine sulphinic acid and 97.5 parts by weight of salt-free water. The activator solution is added dropwise as required.

When 65 to of the monomers have been polymerised, polymerisation is stopped by the addition of a radical acceptor, e.g. tertiary butyl pyrocatechaol, and

EXAMPLE 7 Monomer phase |00.00 Parts by weight of 084 Parts by weight of chloroprene xnathogen disulphide of the following formula C-CH --c-s 2 I C2H5 S 2 Agueous phase I200 Parts by weight of salt-free water 50 Parts by weight of sodium salt of a dispropionated abietic acid 0.5 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 0.5 Parts by weight of sodium hydroxide 0.5 Parts by weight of tetrasodium py rophosphate When the two phases have been mixed, the temperature is adjusted to 43C and polymerisation is initiated with an activator solution consisting of 2.5 parts by weight of formamidine sulphinic acid and 97.5 parts by weight of salt-free water. The activator solution is added dropwise as required.

When 65 to 70% of the monomers have been converted to polymer, polymerisation is stopped by the addition of a radical acceptor, e.g. tertiary butyl pyrocatechol, and the remaining monomers are removed by steam distillation. The Mooney viscosity ML-4'/100C of a sample which has been isolated by electrolyte precipitation and drying is 45.

EXAMPLE 8 (COMPARISON EXAMPLE) Monomer phase l00.00 Parts by weight of chloroprene 0.28 Parts by weight of ndodecylmercaptan Aqueous phase 120.0 Parts by weight of saltfree water 5.0 Parts by weight of sodium salt of a disproportionated abietic acid 0.5 Parts by weight of sodium salt of a condensation product of naphthalene sulphonic acid and formaldehyde 0.5 Parts by weight of sodium hydroxide 0.5 Parts by weight of tetrasodium pyrophosphale Polymerisation is carried out as in Example 1 and 2. The Mooney viscosity ML-4'/ 100C of the resulting polymer is 45.

EXAMPLE 9 (COMPARISON EXAMPLE) Example 4 is similar to Example 3 except that instead of 0.28 parts by weight of mdodecylmercaptan, 0.4 parts by weight of diethylxanthogen disulphide are used. The Mooney-viscosity ML-4'/l00C of the resulting polymer is 45.

ll. PREPARATION OF CROSS-LINKED. BENZENE [NSOLUBLE POLYCHLOROPRENE EXAMPLE 10 The following components are introduced into a 40 litre autoclave which is equipped with stirrer, thermometer, feed tubes and a cooling system:

kg of salt free water kg sodium salt of a disproportionated abietic acid kg sodium salt of a condensation product of alkyl naphthalene sulphonic acid and formaldehyde 0.036 kg sodium hydroxide 0.060 kg letrasodium pyrophosphate When these components have been thoroughly mixed. the following are added:

l0.620 kg of chloroprene L380 kg ethylene glycol dimethacrylate 0.034 kg n-dodecylmercaptan The autoclave contents are then heated to 43C and polymerisation is initiated with dropwise addition of a catalyst solution containing 2.5 g of formamidine sulphinic acid dissolved in 97.5 g of salt-free water.

When approximately of the monomers have been converted to polymer, polymerisation is stopped by the addition of a stabilizer solution of 5 g of phenothiazine. 5 g of p-tert.-butyl pyrocatechol, 500 g of toluene.

The latex is then freed from unreacted monomers by steam distillation. The Mooney viscosity ML-4/ 100C of the polymer if 70.

Ill. PREPARATION OF MIXTURES OF UNCROSS-LINKED AND CROSS-LINKED POLYCHLOROPRENE EXAMPLES ll-l8 In each of Examples 6 9. 55 parts by weight (based on the solids content) of the polymer latices of Examples 1 to 4 are mixed with 45 parts by weight (based on the solids content) of the polymer latex from Example 5, precipitated by freeze coagulation and dried.

In each of Examples 10 l3. parts by weight, (based on the solids content) of the polymer latices of Examples 1 4 are mixed with 15 parts by weight (based on the solids content) of the polymer latex from Example 5. precipitated by freeze coagulation and dried.

The polymer mixtures of Examples 6 to 13 are then mixed with the following components on rollers in the usual manner:

100.0 Parts by weight polymer mixture 29.0 Parts by weight inactive carbon black 0.5 Parts by weight stearic acid 2.0 Parts by weight phenylflmaphthylamine 4.0 Parts by weight magnesium oxide 5.0 Paris by weight zinc oxide 0.5 Parts by weight ethylene thiourea.

The mixtures are vulcanized at l50C for 30 minutes. The vulcanizate obtained in this way have the proper ties shown in Table l.

The results demonstrate convincingly that the highest strengths are obtained when the mixtures contain polymers which have been prepared using the particular xanthogen disulphides.

Table 1 Examples 1 12 13 14 I In 17 1a Tensile strength (kp/cm") DIN 535U4 I21 I22 109 I I5 I40 I53 I31) I33 Elongation at break ir] DIN 53504 445 455 445 45" 560 585 585 55!) Modulus (30(19? elongation in kp/cm) DIN 53504 63 fill 55 57 54 5) 41 4X Shore hardness A at RT DIN 53505 58 57 56 5h 57 56 53 54 Elasticity DIN 53512 54 54 so 51 5: 5s 52 53 we claim wherein X may be the same or different and is selected l A process for producing a chloroprene polymer from the group consisting of hydrogen, alkyl having l comprises p ym rizing 60 to 100 p r y to 6 carbon atoms. phenyl. naphthyl. benz l. chlorine. weight of Chloroprene and 40 to 0 P i b welght P bromine and iodine and n, and n are the same or are m b Selected from the group conslsmlg of a dlene different and are each an integer of from 1 to 20. m Whlch the hydrogen atoms y be Partially of 2. The process of claim 1 wherein R and R are the pletely substituted by halogen atoms. an monoethyleni- Same, cally unsaturated copolymerizable monomer or a mix- 3 Th process f laim 1 wherein the X groups are ture thereof in the presence of 0.05 to 30 parts by 30 h d or lk l h vi I to 6 carbon atoms. welght of an Xamhogen dlsulphlds of the formula 4. The process of claim 1 wherein 0. l 5 to 1.0 part by R,0CSS-C R. weight of said xanthogen disulphide is employed.

8 5. The process of claim 1 wherein the polymerization is liter out in the presence of 0.1 to 0.6% by weight of wherein R and R are the same or different and are of ph based on the monomer g the formula 6. The process of claim I wherein 100 parts by X O H X 0 X weight of chloroprene and 0 parts by weight of said 1 2 i 2 member selected from said group IS employed. x o (cx. or (CX:l,.:

l x X x 

1. A PROCESS FOR PRODUCING A CHLOROPRENE POLYMER WHICH COMPRISES POLYMERIZING 60 TO 100 PARTS BY WEIGHT OF CHLOROPRENE AND 40 TO 0 PARTS BY WEIGHT OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF A DIENE IN WHICH THE HYDROGEN ATOMS MAY BE PARTIALLY OR COMPLETELY SUBSTITUTED BY HALOGEN ATOMS, AN MONOETHYLENICALLY UNSATURATED COPOLYMERIZABLE MONOMER OR A MIXTURE THEREOF IN THE PRESENCE OF 0.05 TO 30 PARTS BY WEIGHT OF AN XANTHOGEN DISULPHIDE OF THE FORMULA
 2. The process of claim 1 wherein R1 and R2 are the same.
 3. The process of claim 1 wherein the X groups are hydrogen or alkyl having 1 to 6 carbon atoms.
 4. The process of claim 1 wherein 0.15 to 1.0 part by weight of said xanthogen disulphide is employed.
 5. The process of claim 1 wherein the polymerization is liter out in the presence of 0.1 to 0.6% by weight of sulphur, based on the monomer weight.
 6. The process of claim 1 wherein 100 parts by weight of chloroprene and 0 parts by weight of said member selected from said group is employed. 